Packages for consumer products known as "blister cards" often include a backing member made of cardboard or other rigid material and a clear plastic product enclosure adhered to one side of the backing member. The clear plastic enclosure, which is commonly referred to as a "blister", is typically thermoformed to conform in size and shape to that of the product being packaged. The enclosure thus securely holds the product in the package and allows the consumer to clearly see the product when making a purchasing decision. The backing member may have information regarding the product, such as promotional or instructional material, printed on one or both sides thereof.
These blister cards may take several forms. For example, U.S. Pat. No. 3,289,830 to Foote entitled Display Card Mounted Retainer and Packaging Device discloses a single or multilayered display card having a thermoformed transparent flexible plastic retainer which is affixed against the front face of the card. Perforations on the back face of the card define flaps and allow the package to be opened and the product thereafter removed through the opening. An instructional ticket may be inserted between the product and the card so that the ticket will be removed prior to removing the product from the package.
Another example is U.S. Pat. No. 4,125,190 to Davie, et al. entitled Child-Resistant Blister Package. Disclosed therein is a foil-backed blister sheet sandwiched between upper and lower card sheets which are heat-sealed together. A third card having a tear strip is heat-sealed against the lower card sheet.
A desirable blister card which may be manufactured according to the process of the present invention includes a backing member made of multiple layers of paperboard. The backing member may have a removable panel in a back layer of the backing member such that when the panel is removed, various ancillary materials are exposed, such as coupons, detailed instructions or security devices. In addition, a clear plastic product enclosure may be adhered to a front layer of the backing member.
In manufacturing the product enclosure, it is often desirable to provide a flange around the peripheral edge thereof so that the enclosure can be heat-sealed to the front layer of the backing member. In addition, it is generally advantageous to use a heat-seal coating between the flange of the enclosure and the backing member to promote adhesion.
When heat-sealing the product enclosure to the backing member, a heated heat-seal head is placed against the back side of the backing member opposite the product enclosure. The heat-seal head corresponds in size and shape to the flange of the product enclosure and cooperates with an unheated supporting member on the front side of the backing member, which may also have a size and shape corresponding to that of the heat-seal head. Accordingly, as the heat-seal head and supporting member are pressed together, heat travels from the head through the backing member so that the flange of the product enclosure is adhered to the front side of the backing member.
Because of the multiple layers and ancillary materials of the backing member manufactured according to the present invention, a generally higher temperature for the heat-seal head is required. In addition, a longer dwell duration for which the heat-seal head must be placed against the backing member may also be required. As a result of the greater heat transfer, however, it is possible for the back layer of the backing member to-become scorched or burned. This is an even greater concern when "coated" paperboard is used, i.e., paperboard which has been treated to have a smooth, glossy finish.
Accordingly, it is an object of the present invention to provide an improved process of manufacturing product packages of this type.
It is another object of the present invention to provide a process for manufacturing product packages having multilayer backing members and a plastic enclosure heat-sealed to a front layer thereof.
It is yet another object of the present invention to provide a process for manufacturing product packages having a multilayer backing member wherein a plastic enclosure is heat-sealed to the backing member without scorching or burning the backing member.